Atmospheric aging and thermal annealing effects in a-C:H thin films

Abstract

Atmospheric aging and thermal annealing effects have been studied in hydrogenated amorphous carbon (a-C:H) thin films deposited using a dc saddle field glow discharge technique with different ion energies (85–225 eV) during deposition. The a-C:H films grown with low ion energies showed aging effects when they were exposed to the ambient atmosphere. Infrared (IR) absorption due to O–H and CO vibration modes increased while the IR absorption due to C–H vibrations decreased with aging. The absence of absorption due to O–D vibrations in deuterated films indicates that the films reacted with water rather than oxygen when exposed to the atmosphere. The C–H and O–H bond concentrations decreased when the a-C:H films which had been exposed to the atmosphere for a one month period were thermally annealed. The a-C:H films grown with high ion energies exhibited neither atmospheric aging nor thermal annealing effects.